•Ag3PO4/CuO nanocomposite was synthesized via in-situ precipitation technique.•The nanocomposite exhibits enhanced photocatalytic activity in RhB degradation.•The Ag3PO4/CuO shows cooperative or synergic effects between Ag3PO4 and CuO.A novel Ag3PO4/CuO nanocomposite photocatalyst was synthesized via a facile in-situ precipitation technique. The as-synthesized products were characterized by XRD, SEM, TEM and UV–vis spectroscopy. The result confirmed that Ag3PO4 and CuO have been composited successfully. The degradation efficiency of Rhodamine B (RhB) over commercial P25 or pure CuO was only about 22% and 46%. Compared with pure Ag3PO4, the Ag3PO4/CuO nanocomposite needed less time to degrade RhB completely, showing the best photocatalytic activity. This enhancement was attributed to the coupling of Ag3PO4 and CuO, which improve the transfer of photoexcited carriers, inhibit their recombination and facilitate the production of more •OH radicals.

Olive-like BiVO4 microstructures with lengths of 600–1000 nm and widths of 300–600 nm have been synthesized via a facile and additive-free solvothermal method. Studies find that the type of solvent plays an important role in the morphology of the final products. Furthermore, Ag3PO4 nanocrystals are successfully deposited on monoclinic olive-like BiVO4 via in situ precipitation method. The as-synthesized samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), photoluminescence (PL) spectra, and UV–vis diffuse reflectance spectra (DRS). The photocatalytic activities of the catalysts are evaluated by degradation of rhodamine B (RhB) and methylene blue (MB) under visible light (≥420 nm) irradiation. The experimental results suggest that catalytic activity of the composite photocatalysts is greatly influenced by the loading level of Ag3PO4. The molar ratio of 0.8:1.0 Ag3PO4-loaded BiVO4 exhibits higher photocatalytic activity in both the decolorization of RhB and MB than that of individual BiVO4 and P25. The observed improvement in photocatalytic activity is associated with the extended absorption in the visible light region resulting from the Ag3PO4 nanoparticles, and the effective separation of photogenerated carriers at the Ag3PO4/BiVO4 interfaces through the formation of heterojunction structure. The study provides a general and effective method in the fabrication of composite with sound heterojunctions that may show a variety of applications.

•A novel electrochemical DNAzyme sensor was developed for Ni2+ detection.•DNAzyme-functionalized CdSe nanocomposite are used as probe.•The biosensor exhibited high sensitivity and fast response to Ni2+.The detection and speciation analysis of metal-ion is very important for environmental monitoring. A novel electrochemical biosensor for Nickel(II) detection based on a DNAzyme-CdSe nanocomposite was developed. We firstly hybridized with capture probe (DNA1) and sequentially with DNA (DNA2) on the gold electrode. Then CdSe QDs were incorporated the specific recognition of DNA2 by covalent assembling. Upon addition of nickel ion into the above system, the substrate strand of the immobilized DNAzyme was catalytically cleaved by target Ni2+, resulting in disassociation of the shorter DNA fragments containing CdSe QDs. The remaining CdSe QDs on the electrode surface detected by differential pulse anodic stripping voltammetry (DPASV). Under optimal conditions, the as-prepared sensor exhibited high sensitivity and fast response to Ni2+ with the linear range from 20 nM to 0.2 mM and a low detection limit of 6.67 nM. The prepared biosensor also shows good stability and good reproducibility and high selectivity toward target Ni2+ against other metal ions because of highly specific Ni2+-dependent DNAzyme. Thus, our strategy has a good potential in the environment surveys.

•Urchin-like Cu3CrO6·2H2O nanostructures have been successfully synthesized.•Urchin-like Cu3CrO6·2H2O nanostructures are composed of hundreds of nanowires.•A possible growth mechanism was discussed.•Room-temperature photoluminescence of the Cu3CrO6·2H2O with different morphologies has also been investigated.Urchin-like Cu3CrO6·2H2O nanostructures have been successfully synthesized via a facile and fast sonochemical route. The composition, morphology and size of the as-obtained product were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high resolution transmission electron microscopy (HRTEM). These results showed that the as-synthesized Cu3CrO6·2H2O urchins have average diameters of 1 μm and an individual urchin sphere is composed of numerous small nanowires. Typical Cu3CrO6·2H2O nanowires have diameters of 5 nm. Studies found that ethylenediamine tetraacetic acid disodium salt (EDTA) plays an important role to determine the morphology of the products. The self-assembly and oriented attachment procedure has been proposed for the possible formation mechanism. The Brunauer-Emmett-Teller (BET) surface area of the urchin-like nanostructures calculated from the nitrogen adsorption–desorption isotherm is about 78 m2 g−1. Additionally, room-temperature photoluminescence of the Cu3CrO6·2H2O with different morphologies has also been investigated.

•Carambolla-like CuO hierarchical nanostructures with diameter of about 200 nm and length of 600 nm have been successfully synthesized.•A possible formation mechanism for carambolla-like CuO nanostructures was proposed.•The nonlinear optical property of carambolla-like CuO nanostructures has also been investigated.Carambolla-like CuO hierarchical nanostructures with diameter of about 200 nm and length of 600 nm have been successfully synthesized through a fast and facile sonochemical method. The morphology, crystallinity and size of the as-prepared products were confirmed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). The growth mechanism of carambolla-like CuO nanostructures is discussed by monitoring different reaction times. It is shown that the carambolla-like CuO nanostructures are formed through oriented attachment of nanowires. In addition, the nonlinear optical property of carambolla-like CuO nanostructures has also been investigated, indicating that these nanomaterials have potential future application in nonlinear optics.

•Self-assemble Mn(PAN)2 hierarchical superstructure have been synthesized by a facile solvothermal route.•The morphologies were greatly influenced by reaction parameters.•The formation mechanism was investigated.Highly ordered self-assembled Mn(PAN)2 hierarchical superstructure assembled by nanobelts with width of 100–400 nm and length of 4–5 μm has been synthesized via a facile and additive-free solvothermal method. The as-synthesized Mn(PAN)2 was characterized by elemental analysis (EA), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The solvent type and reaction time play an important part in the morphologies of the final sample. A possible growth process for self-assembled Mn(PAN)2 hierarchical superstructure is proposed. It is shown that the self-assembled Mn(PAN)2 hierarchical superstructure was formed through oriented attachment of nanobelts.

A novel graphene oxide nanosheets/polyaniline nanowires/CdSe quantum dots (GO/PANi/CdSe) nanocomposites are successfully synthesized and use as ECL immunosensor for detection of human interleukin-6 (IL-6). The as-prepared GO/PANi/CdSe nanocomposites show excellent biocompatibility, dispersity and solubility. Electrochemiluminescence (ECL) of CdSe quantudm dots (QDs) was greatly enhanced by combining with GO/PANi nanocomposites. Herein, this GO/PANi/CdSe nanocomposite was applied to develop an ultrasensitive ECL immunosensor for detection of IL-6. The ECL immunosensor has a sensitive response to IL-6 in a linear range of 0.0005–10 ng mL−1. The prepared ECL immunosensor exhibits high specificity, long-term stability and excellent reproducibility with a detection limit of 0.17 pg mL−1.Scheme of multistep synthesis of hybrid GO/PANi/CdSe QDs nanocomposites (A) and the fabricating steps of the ECL immunosensor (B).

A novel graphene oxide sheets/polyaniline/CdSe quantum dots (GO/PANi/CdSe) nanocomposites were successfully synthesized and used for the sensitive electrochemiluminescence (ECL) biosensing. The GO/PANi/CdSe nanocomposites were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), ultraviolet–visible (UV–vis) absorption spectroscopy, photoluminescence (PL) spectroscopy and Fourier transform infrared (FTIR) spectroscopy. Finally, the nanocomposites were employed to construct the biosensor via layer-by-layer assembly for the ECL detection of Cytochrome C (Cyt C). The whole process was characterized by cyclic voltammogram (CV) and electrochemical impedance spectroscopy (EIS). Experimental parameters such as the ratio of GO/PANi, the K2S4O8 concentration and the pH value of electrolyte solution were studied to investigate the effect on the ECL intensity. Under the optimized conditions, the ECL intensity decreased linearly with the Cyt C concentrations in the range from 5.0×10−8 to 1.0×10−4 M with detection limit of 2.0×10−8 M. Besides, the as-proposed biosensor exhibits high specificity, good reproducibility, and stability, and may be applied in more bioanalytical systems.Highlights► The graphene oxide sheets/polyaniline/CdSe quantum dots (GO/PANi/CdSe) nanocomposites were successfully synthesized. ► The GO/PANi/CdSe nanocomposites have high ECL intensity and long-term stability. ► The constructed ECL biosensor exhibited high sensitivity and good selectivity to cytochrome C.

Zn(PAN)2 nanobelts with widths of 100–200 nm and lengths of 1–2 μm have been successfully synthesized through a facile solvothermal method at 140 °C for 24 h. The composition, morphology and size of the as-prepared products were confirmed by elemental analysis (EA), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The effects of Zn/PAN molar ratio, reaction solvent and reaction time on the morphology of Zn(PAN)2 nanostructures have been studied systematically. A possible growth process of the Zn(PAN)2 nanobelts has been proposed. Moreover, the nonlinear optical property of the Zn(PAN)2 sample was investigated for the first time, indicating that these nanomaterials have potential future application in nonlinear optics.

8-Hydroxyquinoline cadmium (Cdq2) nanobelts with width of 100–200 nm and lengths of 0.5–2 μm have been successfully synthesized through a facile solvothermal method at 120 °C for 24 h. The composition, morphology and structure of the as-prepared products were confirmed by X-ray powder diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Experiment results indicated that the concentration of ethanol played an important effect in the morphology of the final products. Moreover, the electrogenerated chemiluminescence (ECL) properties of the Cdq2 sample with different morphologies were investigated. The ECL spectra show that the Cdq2 nanobelts exhibited excellent electrogenerated chemiluminescence (ECL) behavior.Highlights► 8-hydroxyquinoline Cadmium (Cdq2) nanobelts have been successfully synthesized. ► The concentration of ethanol plays an important effect in the morphology of the final product. ► The as-prepared Cdq2 nanobelts exhibited excellent electrogenerated chemiluminescence (ECL) behavior.

SrWO4 nanobelts have been synthesized via a facile and fast sonochemical route. The samples were characterized by XRD, SEM and TEM techniques. Experimental results showed that the concentration of Na2EDTA and high-intensity ultrasonic irradiation played important roles in controlling the morphologies of SrWO4. Room-temperature photoluminescence of SrWO4 with various morphologies have also been investigated. Results showed that SrWO4 nanobelts possessed good photoluminescent properties, suggesting that SrWO4 nanobelts could be used in novel optoelectronic devices.

•Uniform, water-soluble and nontoxic N-C QDs were firstly synthesized.•DNA functionalized N-C QDs as signal enhancers to construct an ultrasensitive ECL biosensor to detect miRNA-21.•Nicking enzymes (Nb.BbvCI) were utilized to trigger target cycling reaction to realize efficient signal amplification.An ultrasensitive electrochemiluminescence (ECL) biosensor for the detection of microRNA was developed based on nicking enzymes Nb.BbvCI mediated signal amplification (NESA). First, the hairpin probe1-N-CQDs with assistant probe and microRNA (miRNA) formed Y junction structure which was cleaved with the addition of nicking enzymes Nb.BbvCI to release miRNA and assistant probe. Subsequently, the released miRNA and assistant probe can initiate the next recycling process. The generation of numerous intermediate sequences nitrogen doped carbon quantum dots-DNA (N-CQDs-DNA) can further hybridize with hairpin probe2 immobilized on GO/Au composite modified electrode surface, the initial ECL intensity was enhanced. The ECL intensity would increase with increasing concentration of the target miRNA, and the sensitivity of biosensor would be promoted because of the efficient signal amplification of the target induced cycling reaction. The novel designed biosensor provided a highly sensitive and selective detection of miRNA-21 from 10 aM to104 fM with a relatively low detection limit of 10 aM. Thus, our strategy has a potential application in the clinical diagnosis.